ASCP Tissue Fixation and Decalcification 2

Question 1

Which fixative type is most likely to mask antigenic epitopes, necessitating antigen retrieval before immunohistochemistry?

Accepted Answer

10% neutral buffered formalin

Answer

Absolute ethanol

Answer

Acetone

Answer

Methanol

Question 2

Zenker's fixative contains which hazardous heavy metal component?

Accepted Answer

Mercuric chloride

Answer

Lead acetate

Answer

Arsenic trioxide

Answer

Cadmium sulfate

Question 3

Which fixative is preferred when preservation of glycogen in tissue is the primary concern?

Accepted Answer

Absolute alcohol (ethanol)

Answer

10% neutral buffered formalin

Answer

Carnoy's fixative

Answer

Bouin's solution

Question 4

What is the ideal pH range for neutral buffered formalin to prevent artifact formation?

Accepted Answer

6.8–7.4

Answer

5.0–6.0

Answer

6.0–6.8

Answer

7.4–8.0

Question 5

What is formalin pigment and how is it prevented?

Accepted Answer

A brown artifact from acidic formalin reacting with hemoglobin; prevented by using buffered formalin

Answer

A yellow discoloration from picric acid; prevented by washing in tap water

Answer

A blue artifact from alkaline formalin; prevented by using unbuffered formalin

Answer

A black deposit from osmium tetroxide; prevented by shortening fixation time

Question 6

What is the recommended tissue-to-fixative volume ratio to ensure adequate fixation?

Accepted Answer

1:10

Answer

1:1

Answer

1:5

Answer

1:20

Question 7

Ethanol (absolute alcohol) is classified as which type of fixative based on its mechanism of action?

Accepted Answer

Non-additive coagulant fixative

Answer

Additive cross-linking fixative

Answer

Oxidizing fixative

Answer

Metallic fixative